Thunder, snow, sleet and lightning: Even meteorologists admit this Mississippi storm was one for the ages

Snow, sleet and rain all at the same time? It's not something Mississippians see very often.

Throw in thunder and lightning and the fact that it happened while temperatures were in the low 20s and you have layers of confusion, with the key word being "layers."

"What we have is an unusual bitter-cold air mass coming from the Arctic," said Logan Poole, meteorologist with the National Weather Service in Jackson. "Arctic air is unusually dense, but it's not very deep."

The Arctic air is one of three layers contributing to this week's weather. The thin Arctic layer is at the bottom and is what is making everything below it drop to brutal temperatures. At the very top is another very cold layer and in between is a mass of warmer air.

Poole said the Arctic air originated in far Northwest Canada and was 30-50 degrees colder than normal from the start. He said it's unusual enough for Arctic air to reach this far south, but for it to happen at a time when it was so much colder than normal is an extremely rare event.

"The craziest part is how cold that air got where it was and then to get down to Mississippi," Poole said. "That just doesn't happen that often."

POWER OUTAGES:Thousands in Mississippi without power 

The science of layers 

"Right now we're sitting here at 22 degrees in Jackson," Poole said Tuesday morning. "The air a few hundred to a few thousand feet is warmer.

"When we sent our weather balloon up it was 45 degrees. This weather is not usual at all."

Poole explained what we experienced: Frozen precipitation fell from the cold upper layer. As it passed through the warm middle layer, it changed to rain. Then, as it passed through the Arctic layer it froze again in the form of sleet and snow — or at least most of it did.

Poole said the Arctic layer really is shaped like a wedge with one end being thicker than the other. Some of the rain above the thinner parts of the wedge didn't have time to freeze before passing through, so it fell to the ground and then froze. 

WINTER STORM:One death, multiple vehicle pileups reported across Mississippi as winter weather worsens

Thunder, lightning and odd 'snowflakes'

Of course, let's not forget the thunder and lightning. Thunderstorms are all too common in Mississippi during warmer seasons, but when the temperatures are near the 20-degree mark, not so much. Once again, Poole said the warm layer of air trapped between two colder layers was the culprit.

"The thunderstorms aren't aware it's 20 degrees outside," Poole said. "That warm air is what the thunderstorms are using for their fuel."

Another aspect may have gone unnoticed by some: There were periods of snow in some areas that almost appeared to be a mist. The flakes weren't like what most people think of snowflakes; instead, they looked more like tiny rods. Poole said those differed from the other precipitation because they formed from moisture within the Arctic air rather than moisture passing through.

"We call those snow grains or snow columns," Poole said. 

Put it all together and you have one of the more unusual weather events Mississippi has seen.

"It's not just rare for us, it's rare for a lot of people — truly incredible weather," Poole said. "It will certainly be a benchmark that other weather is measured against."

Contact Brian Broom at 601-961-7225 or bbroom@gannett.com.